Magnetic core matrix



July 26, 1966 INVENTOR. EVERT VAN DER HOEK BY .22. A if AGENT United States Patent 3,263,221 MAGNETIC CORE MATRIX Evert van der Hock, Hengelo, Overijssel, Netherlands, assignor to N.V. Hollandse Signaalapparaten, Hengelo,

Overijssel, Netherlands, a firm Filed Jan. 21, 1963, Ser. No. 252,934

Claims priority, application Netherlands, Jan. 22, 1962,

Claims. (Cl. 340-174) This invention relates to a storage matrix composed of magnetic cores in which the cores can be made inoperative as storage means by placing a permanent magnet in the vicinity of a core which is desired to be made inoperative.

A permanent magnet used in this manner saturates the core to be made inoperative to such an extent that the currents which flow in the circuits coupling this core for writing and reading are unable to cause a substantial change in the magnetization of such a core. Thus, when a line in a matrix to which such a core belongs is read out, this core does not induce a measurable voltage pulse in the sense wire coupled therewith.

Consequently the core no longer operates as a storage means.

In storage matrices of this type the separation between the cores must be greater than is normally necessary for only the cores and the wiring. This is true primarily because a permanent magnet which is to make a certain core inoperative will also induce a field in the nearby cores of the matrix. It the distance between the cores is too small this field will be strong enough to reduce the reliability of the storage operation of a nearby core. The magnetic fields induced in a core during the reading and writing operations have opposite directions. In a nearby core, one of these fields is increased by the stray field of the said permanent magnet, while the other field is decreased by it. The latter field may then have insuificient strength to cause a reversal of the core magnetization. Experience has shown that nearby cores may actually be influenced in this way, with the result that such nearby cores will not operate correctly at all times, depending on small variations of various parameters, such as the supply voltages, temperature, etc.

It has also been observed that a certain core which has been made inoperative by means of such a permanent magnet will sometimes become operative again if the distance between adjacent cores is too small and a fairly large number of the cores in the vicinity of the certain core have also been made inoperative. The flux of a permanent magnet used to make a certain core inoperative passes through this core and then back again to the magnet through the space between the cores. If the space between adjacent cores is small the density of the flux in spaces between a number of cores which have been made inoperative becomes so high that maintaining the field in the said space requires too large a part of the available magneto-motive force of a permanent magnet of the type used for this purpose; as a result, the field strength in a core to be made inoperative may become too low to keep this core inoperative under all conditions.

A primary object of the invention is to provide a core storage matrix wherein cores are made inoperative as storage means by the use of permanent magnets and in which the dimensions of the matrix are as small as those of a matrix in which such permanent magnets are not used.

In the core storage matrix according to one aspect of the invention, a soft iron plate extends along the surface of the matrix at the side remote from that where the permanent magnets for making cores inoperative are 3,263,221 Patented July 26, 1966 situated and in the vicinity of each core that can be made inoperative, at least one soft iron rod extends from the side of the matrix where the permanent magnets are situated to the side where the soft iron plate is mounted at the latter side these rods reach at least the immediate vicinity of the said plate.

The soft iron rod and the soft iron plate together form a return path for the flux of the permanent magnets used for making the cores inoperative; this return path is so effective that, even if the other cores in the immediate vicinity of a certain core have all been made inoperative, the maintaining of the flux in the return path through the plate and the rod requires only a small part of the magneto-motive force which can be supplied by a permanent magnet of the type used. Consequently, a matrix core made inoperative by a permanent magnet according to the invention will not be made operative again by the fields of the magnets making adjacent cores inoperative. Moreover, the use of the rod prevents the operation of a core which is not desired to be made inoperative from becoming unreliable as a result of the presence of cores which have been made inoperative in the vicinity of the said operative core. The stray fields of the magnets which make the latter cores inoperative pass for the greater part through the soft iron rods, and the small remaining part of the stray field is not great enough to impede the operation of a nearby operative core.

In a preferred aspect of the invention, each soft iron rod has one end abutting the soft iron plate.

It is not necessary for the matrix to include a separate soft iron rod for each core which can be made inoperative. Experience has shown that a number of cores can use a common soft iron rod as a return path for the flux. An embodiment in which one single soft iron rod is mounted in the space between four adjacent cores has been found to be very effective.

The effectiveness of the matrix according to the invention can be further increased by mounting a second soft iron plate at the side of the matrix where the magnets are situated. Such a plate can also be used as a locking plate for the magnets in order to prevent such magnets from physically leaving their positions in the matrix.

The invention will be better understood from the following description thereof when read with reference to the accompanying drawings wherein:

FIGURE 1 shows a cross section of a matrix aceording to the invention.

FIGURE 2 shows a front elevation of such a matrix after the soft iron plate has been removed.

FIGURE 1 shows a cross section of the matrix according to the invention along a plane which is perpendicular to the plane of the matrix and at an angle of 45 degrees both to the direction of the read and write wires and to the direction of the wires effecting the selection of the lines in the matrix. Consequently the ring shaped cores 1, 2, 3, 12 and 13 are actually shown in circular shape. The cores 1, 2and 3 are in the plane of the drawing. Each core is situated in a rectangular opening, such as 18, of a supporting plate 4 of the matrix. The cores and the matrix wires are glued to this plate. The wiring is not shown in FIGURE 1. A soft iron plate 9 extends along the surface of the matrix in the vicinity of the cores. A guiding plate 7 for guiding and supporting the permanent magnets used for making cores inoperative as storage means is mounted against the supporting plate 4. Holes such as shown by reference numeral 5 are located in guiding plate 7 in front of each opening in the supporting plate used to support a core, such as the opening 18. These holes have such dimensions that a permanent rod magnet can narrowly fit in each. Reference numerals 6 and 8 show such a permanent rod magnet mounted in a hole of the guiding plate 7. These magnets are situated with their right hand ends in the immediate vicinity of or abutting a ring-shaped core and with their left hand ends in the immediate vicinity of or abutting the soft iron locking plate 14.

A soft iron rod 10 is located in the space between the ring shaped cores 1 and 2. It passes through an opening in the supporting plate 4 and a hole in the guiding plate 7. The right hand end of the rod 10 rests against the soft iron plate 9, while the left hand end is in the immediate vicinity of or abuts the soft iron locking plate 14. The flux of the magnet 6 passes through the ring 1, through the small air gap between ring 1 and plate 9, to the plate 9, and back to the permanent magnet 6 through the soft iron rod 10 and the soft iron plate 14. It is not absolutely necessary to provide the matrix with the iron plate 14. An alternative embodiment using a copper locking plate is also very effective. Such copper plate locks the magnets in their positions in the matrix and, by the eddy current effect, shields the matrix from the influence of alternating magnetic fields generated by adjacent apparatus however, the copper plate does not provide a return path for the flux of the permanent magnets. Near the left hand end of the matrix, however, so much space is available for the flux that even if all the cores around the core 1 are made inoperative by means of permanent magnets the density of the flux will still remain so low that it will not require too large a part of the magneto-motive force supplied by the permanent magnets. No soft iron rod is present in the interspace between the cores 2 and 3. A magnet introduced into the opening in order to render the ring shaped core 2 inoperative will also use the rod as the return path for its flux. This is feasible because of the high permeability of the soft iron rod. The next rod in the row of cores 1, 2 and 3 is the rod 11, which is situated below the core 3 and is used to provide a return path for the field of permanent magnets co-acting with the core 3 and the core not shown and situated below the rod 11.

FIGURE 2 shows the same matrix in front elevation after the plate 9 has been removed. The cross section of FIGURE 1 is taken along line 20 of FIGURE 2. Arrow 17 shows the direction of one of the sides of the matrix and of one of the sets of read and write wires constituting the wiring of the matrix. FIGURE 2 shows the matrix wiring as solid lines between the cores and also shows the distribution of the rods in the matrix. Rod 10 supplies the return path for the flux of the rod magnets used for rendering the cores 1, 2, 12 and 19 inoperative. In the same way rod 11 serves as the return path for the flux of the permanent magnets used for rendering core 3 and the other three cores situated around rod 11 inoperative. Only two of these latter cores are shown.

In a similar way the rods and 1d are used as return paths for the cores arranged around these rods. Even if all the four cores situated around such a rod are made inoperative by means of permanent magnets, the magnetomotive force required for maintaining the flux in this rod nevertheless remains low due to the high permeability of the soft iron rod. On the other hand, a rod such as 10 attracts so large a part of the stray flux of a magnet such as 6 (co-acting with core 1) that the remaining stray flux is unable to unduly influence the reliable operation of adjacent cores such as 2, 12 and 19. The minimum pattern of soft iron rods cannot be maintained near the edges of the matrix if all the cores in the vicinity of the edge are to be provided with a suitable return path for the flux of the magnets which can be used to make said cores inoperative. In this case a number of extra rods must be provided. It will be clear that, apart from these extra rods near the edges the matrix can easily be provided with a larger number of soft iron rods than are present in the embodiment described above; however, this is generally not necessary and offers no particular advantages.

The particular manner in which the soft iron plates 14! and 9 are mounted on the matrix does not form a part of this invention. As an example, studbolts may be secured by means of nuts in openings at various points near the edge of the plate 4. The plates 9 and 14 may be provided with openings at corresponding positions and mounted on these studbolts by means of distance rods and nuts.

While the invention has been described with respect to specific embodiments, various modifications thereof will be readily apparent to those skilled in the art without departing from the inventive concept, the scope of which is set forth in the appended claims.

What I claim is:

1. In combination: a plurality of magnetic storage cores constituting a matrix having an upper side and a lower side, a plurality of permanent magnets each of which co-acts with a selected core, each co-acting permanent magnet being located near the upper side of the matrix with one pole in close proximity to a selected core, at least one soft magnetic plate extending along the lower side of the matrix, a plurality of soft magnetic rods, each rod being located in a space in the matrix between a plurality of cores with one end in close proximity to said plate and extending from the plate to the upper side of the matrix.

2. The combination of claim 1 wherein said one end of each rod abuts said plate.

3. The combination of claim 1 wherein the number of rods is less than the number of cores.

4. In combination: a plurality of magnetic storage cores constituting a matrix having an upper side and a lower side, a plurality of permanent magnets each of which co-acts with a selected core, each co-acting permanent magnet being located near the upper side of the matrix with one pole in close proximity to a selected core, a first soft magnetic plate extending along the lower side of the matrix, a second soft magnetic plate extending along the upper side of the matrix, the second pole of each co-acting permanent magnet being in close proximity to said second plate, a plurality of soft magnetic rods, each rod being located in a space in the matrix between a plurality of cores and having one end in close proximity to said first plate and the other end in close proximity to said second plate.

5. In combination: a plurality of magnetic storage cores constituting a matrix having an upper side and a lower side, a plurality of permanent magnets each of which co-acts with a selected core, each co-acting permanent magnet being located near the upper side of the matrix with one pole in close proximity to a selected core, a first soft magnetic plate extending along the lower side of the matrix, a second soft magnetic plate extending along the upper side of the matrix, the second pole of each co-acting permanent magnet abutting said second plate, a plurality of soft magnetic rods less in number than said cores, each rod being located in a space in the matrix between a plurality of cores and having one end abutting said first plate and the other end abutting said second plate.

References Cited by the Examiner UNITED STATES PATENTS 11/1957 Davis 235-l54 10/1962 Smith 340174 

1. IN COMBINATION: A PLURALITY OF MAGNETIC STORAGE CORES CONSTITUTING A MATRIX HAVING AN UPPER SIDE AND A LOWER SIDE, A PLURALITY OF PERMANENT MAGNETS EACH OF WHICH CO-ACTS WITH A SELECTED CORE, EACH CO-ACTING PERMANENT MATRIX BEING LOCATED NEAR THE UPPER SIDE OF THE MATRIX WITH ONE POLE IN CLOSE PROXIMITY TO A SELECTED CORE, AT LEAST ONE SOFT MAGNETIC PLATE EXTENDING ALONG THE LOWER SIDE OF THE MATRIX, A PLURALITY OF SOFT MAGNETIC RODS, EACH ROD BEING LOCATED IN A SPACE IN THE MATRIX 